title: Serum estradiol and testosterone levels in kidney stones disease with and without calcium oxalate components in naturally postmenopausal women.
abstract: OBJECTIVE
  Epidemiological data reveal that the overall risk for kidney stones disease is lower for women compared to age-matched men. However, the beneficial effect for the female sex is lost upon menopause, a time corresponding to the onset of fall in estrogen levels. The aim of this study was to describe the serum estradiol (E2) and testosterone (T) characteristics of naturally postmenopausal women with kidney stones.
  
  
  METHODS
  113 naturally postmenopausal women with newly diagnosed kidney stones (aged 57.4±4.98 years) and 84 age frequency matched stone-free controls (56.9±4.56 years) were validly recruited in the case-control study. The odds ratios (ORs) for the associations between sex hormones and kidney stones were estimated with logistic regression models, adjusting for demographic data and medical history. Patients were also stratified analyzed according to stone components (calcium oxalate stones [COS]; non-calcium oxalate stones [NCOS]).
  
  
  RESULTS
  Serum E2 (21.1 vs. 31.1 pg/ml) was significantly lower in kidney stones patients compared to controls. Post-hoc analysis demonstrated that this effect was driven by COS patients (p<0.001). According to tertiles of the E2 levels, a significant higher frequency of COS was seen in the lowest E2 group (p <0.001). Multiple logistic regression analysis identified E2 level as a strong factor that was independently associated with the risk for COS (per 1 SD increase, OR=0.951, 95% confidence interval [CI] = 0.919-0.985; highest: lowest tertile, OR=0.214, 95%CI = 0.069-0.665). However, serum T levels did not significantly differ among the groups.
  
  
  CONCLUSIONS
  Naturally postmenopausal women with higher remaining estradiol levels appear less likely to suffer from kidney calcium oxalate stones. However, no correlation was found between serum T level and kidney stones. These findings support the hypothesis that higher postmenopausal endogenous estrogens may protect against kidney stones with ageing.
authors.affiliation: Department of Urology, Minimally Invasive Surgery Center, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China ; Guangdong Key Laboratory of Urology, Guangzhou, China.
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Zhao
authors.forename: Zanlin
authors.initials: Z
authors.lastname: Mai
authors.forename: Lili
authors.initials: L
authors.lastname: Ou
authors.forename: Xiaolu
authors.initials: X
authors.lastname: Duan
authors.forename: Guohua
authors.initials: G
authors.lastname: Zeng
mesh_terms: D000368:Aged; D000375:Aging / Q000097:blood; D002129:Calcium Oxalate / Q000737:chemistry*; D016022:Case-Control Studies; D004958:Estradiol / Q000097:blood*; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000097:blood / Q000209:etiology*; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood; D012306:Risk; D013739:Testosterone / Q000097:blood*
chemical_list: D002129:Calcium Oxalate; D013739:Testosterone; D004958:Estradiol